SOX9, also named as Transcription factor SOX-9, is a 509 amino acid protein. Sex-determining region Y (SRY)-box 9 protein (SOX9) is a member of the SOX family of transcription factors (TFs) which are developmental regulators that possess high mobility group (HMG) box DNA binding and transactivation domains. It participates in a variety of functions, such as lineage restriction and terminal diferentiation, through precise temporal and spatial expression patterns that difer between particular cell types and tissues. SOX9 gene has been implicated in different types of cancer as an oncogene; however, it also may behave as a tumor suppressor.